So, I'm still waiting for the circuit board to arrive, but I've gotten some preliminary work done on the shell.
Microswitches mounted to the Eject and Reset buttons so that they might serve a purpose, and USB jumpers mounted to the controller ports. (I am going to need to shorten those at some point.) A 3rd USB port is planned to be mounted inside the cartridge slot, but until I can get that planned out, the USB in controller slot 2 should work just as well.

If everything goes according to plan, this is all the cosmetic differences there will be.

I have ordered a Raspberry Pi 3 Model B to use inside this thing, and have already downloaded everything that I should need.
...It just needs to arrive...

I've been wanting to make a Raspberry Pi emulation machine for a little while. I haven't gotten around to it yet. But I've got my old consoles still and I'm buying a CRT television today, so I'm good on that front for now.